Heat-shrinkable polyester-based film roll

Abstract

[PROBLEMS] It is an object of the present invention to provide a heat-shrinkable polyester-based film roll which can reduce defects caused during a heat shrinking step due to the variation of a heat shrinkage rate in the heat-shrinkable polyester-based film roll having the longitudinal direction as the main shrinkage direction, specifically, defects of the film when covering an object by a wrap-around method and heat-shrunk. [SOLUTIONS] A heat-shrinkable polyester-based film roll, comprising a core; and a heat-shrinkable polyester-based film having a longitudinal direction as a main shrinkage direction that is wound around the core; wherein the film (roll) satisfy predetermined polyester composition, and all samples cutout every about 100 m have a heat shrinkage rate measured by immersion in hot water of 90° C. for 10 seconds of 30% or more and 80% or less and ±3% or less of an average in the longitudinal direction.

The invention claimed is: 
     
         1 . A heat-shrinkable polyester-based film roll, comprising
 a core; and   a heat-shrinkable polyester-based film having a longitudinal direction as a main shrinkage direction that is wound around the core;   wherein the heat-shrinkable polyester-based film and the heat-shrinkable polyester-based film roll satisfy the following requirements (1) to (4):   (1) the heat-shrinkable polyester-based film comprises a polyester including ethylene terephthalate as a main constituent component, and at least one polyhydric alcohol selected from a group consisting of 1,4-cyclohexanedimethanol, neopentyl glycol, 1,4-butanediol, diethylene glycol, and 1,3-propanediol;   (2) all test piece films with a square of 10 cm×10 cm have a heat shrinkage rate in the longitudinal direction of 30% or more and 80% or less by immersion in hot water of 90° C. for 10 seconds followed by immersion in water of 25° C. for 10 seconds, wherein the test piece films are cutout at a center position in a roll width direction, and include   a first sample that is cutout from a portion provided at a position within 2 m on an inner side of a second end portion provided at an end of the film roll on a winding end side (surface layer side),   a final sample that is cutout from a portion provided at a position within 2 m on an inner side of a first end portion provided at an end of the film roll on a winding start side (core side), and   other samples that are cutout from a portion provided every about 100 m from the first sample cutout portion;   (3) all the test piece films have a heat shrinkage rate in the longitudinal direction of ±3% or less of an average heat shrinkage rate calculated from the heat shrinkage rates in the longitudinal direction measured by the method described in requirement (2); and   (4) the heat-shrinkable polyester-based film comprises fine particles in an amount of 300 to 1200 ppm in the heat-shrinkable polyester-based film.   
     
     
         2 . The heat-shrinkable polyester-based film roll according to  claim 1 , further satisfying the following requirements (5) and (6):
 (5) all the test piece films have a heat shrinkage rate in a width direction corresponding to a direction orthogonal to the longitudinal direction of −20% or more and 20% or less measured by the method described in requirement (2); and   (6) all the test piece films have a heat shrinkage rate in the width direction of ±3% or less of an average heat shrinkage rate calculated from the heat shrinkage rate in the width direction measured by the method described in requirement (2).   
     
     
         3 . The heat-shrinkable polyester-based film roll according to  claim 1 , wherein the heat-shrinkable polyester-based film has an effective winding length of 1000 m or more and 20000 m or less. 
     
     
         4 . The heat-shrinkable polyester-based film roll according to  claim 1 , wherein the heat-shrinkable polyester-based film has a width of 300 mm or more and 2500 mm or less. 
     
     
         5 . The heat-shrinkable polyester-based film roll according to  claim 1 , wherein the heat-shrinkable polyester-based film has a thickness of 5 μm or more and 100 μm or less. 
     
     
         6 . The heat-shrinkable polyester-based film roll according to  claim 1 , further satisfying the following requirement (7):
 (7) all the test piece films prepared by the method described in requirement (2) have an amorphous component in an amount within a range of ±2 mol % or less of an average amount of the amorphous component of all the test piece films.   
     
     
         7 . The heat-shrinkable polyester-based film roll according to  claim 1 , wherein the fine particles have an average particle diameter within a range of 0.05 to 3.0 μm as measured by a Coulter counter.